1. Field of the Invention
This invention is related in general to mining systems and, in particular, to a novel approach for dispatching mine trucks from the mining site to the appropriate destination according to a predetermined mine development plan.
2. Description of the Related Art
Surface mine development plans outline a proposed mining sequence according to the quality of the ore and mining conditions present in various parts of the mining property. As one skilled in the art would readily understand, drill-core samples are routinely taken from the mine property and assayed to assess the mineral content and rock characteristics of various regions within the mine boundary. Based on these data, three-dimensional maps of the mine are developed showing various properties of interest, such as the average mineral content, as a function of depth and location within the mine property. For example, referring to the drawings, wherein like parts are designated throughout with like numerals and symbols, FIG. 1 illustrates a horizontal mining-plan map for a given vertical elevation in the mine, wherein blocks A-F have been defined on the basis of substantially uniform ore concentration within each block (shown as 0.09, 0.05, 0.002, 0.10, 0.07, and 0.12, respectively). FIG. 2 illustrates the same kind of information along a vertical section of the mine. This information is used to determine an optimal sequence of extraction and downstream processing of the mined material based on market and operating conditions. For instance, current market conditions and operating costs may prevent the economic extraction of material below a predetermined depth in the mine pit. Thus, the mining plan would reflect the fact that no extraction should take place below that depth. Mine plans are updated on an ongoing basis as new data are generated while extraction progresses.
One of the most important economic variables in a surface mine operation is the routing of the mined material to the appropriate destination for further processing. Depending on the quality of the material, it may be appropriate to route it to a smelter, or a leach field, or a dump area, and the correct routing is obviously critical to the economic welfare of an operation. The mine development plan delineates three-dimensional blocks of material based on average properties of neighboring sections that have been assayed during development. The plan prescribes the destination of the material mined from each block so as to optimize the mine""s operation and profitability. To that end, in practice the various blocks are staked out by visible markers separating one block from the other, so that the operator of an excavating machine has direct knowledge of the source of the mined material within the mining plan and can accordingly dispatch the driver of a haulage truck to the correct destination. For example, referring to FIG. 1, ore mined from block A could be dispatched to a smelter because of its high mineral content, while material from block C would be sent to the dump because current operating costs and market conditions would not justify its exploitation.
Thus, in essence, the operator of the excavation machine makes a determination about the intended destination of a particular load based on visually acquired information and so informs the driver of the corresponding haulage vehicle. Because of the human factor involved in this dispatching process, errors are easily made and difficult to recognize and correct. Surface markers, such as stakes and tapes laid out on the surface between mining blocks, can become dislodged by equipment, wind and dirt slides; in addition, machine operators can become distracted by more pressing demands requiring their attention. All of these factors contribute to a large number of unchecked misroutings of mined material. It has been estimated that about 30% of the material extracted in a surface mine has typically been misdirected to the wrong downstream processing location. For example, commercial-grade ore has been sent to the dump and poor material to a smelter. The resulting economic losses have been of great magnitude, often sufficient to affect the viability of a mine.
Since this problem has been recognized, efforts have been made to improve the performance of operators and significant gains have been claimed by the use of systems that aid the operators of excavating machines minimize such mistakes. For example, one such system, disclosed in U.S. Pat. No. 5,850,341, incorporates the mining plan in a computerized database, monitors the position of the mining bucket with a global positioning system (GPS) unit, determines the corresponding block being mined from the mining plan, and alerts the machine operator of the correct source of the mined material. Based on this information, the operator then instructs the driver of the corresponding haulage vehicle about the intended destination of its load.
In spite of the improvement provided by this system, a serious problem remains because of the human factor involved in the steps of acquiring information from the system, using it to instruct the driver of a haulage truck, and implementing the instruction to deliver the load to the correct destination. Therefore, there is still a need for a foolproof system that is not as dependent on human factors as those implemented in the prior art. The present invention provides a procedure and an apparatus for overcoming the deficiencies of prior-art practices.
The primary objective of this invention is a secure system for dispatching mined material to the appropriate destination according to a predetermined mine development plan.
Another objective is an approach that minimizes the occurrence of errors by reducing human participation in the implementation of the dispatching system.
Still another objective is a dispatching system that also provides information for updating the current reserves left unmined in various regions of the mine, thereby providing an ongoing inventory of all production streams associated with the mining plan.
Another goal is a system that is suitable for implementation within an automated haulage and mining system.
Yet another object is a system that can be implemented using hardware developed for the automated operation of a surface mine.
A final objective is a system that can be implemented easily and economically according to the above stated criteria.
Therefore, according to these and other objectives, the preferred embodiment of the present invention consists of linking positioning-system units mounted on mining and haulage equipment to a computerized mine development plan for ascertaining the origin of mined material and directing its disposition according to a predetermined downstream-processing plan. A destination signal is automatically communicated to the haulage vehicle, which is then autonomously guided to the correct destination and tracked until the load is released after arrival. If the haulage vehicle is manually operated, the destination signal and the vehicle""s progress toward it are preferably also displayed on a monitor for the operator""s information and use. The system may further include hardware for blocking the release of a load from the haulage vehicle until and unless the vehicle has reached the prescribed destination.
According to another aspect to the invention, the weight of each load mined and transported to a given target destination is measured by weight sensors in the haulage vehicles (or estimated based on the size of the equipment) and accounted for to update the ore reserves remaining in the various blocks of the mining plan. The same information can advantageously be used to keep track of inventories and production data for downstream operations.
Various other purposes and advantages of the invention will become clear from its description in the specification that follows and from the novel features particularly pointed out in the appended claims. Therefore, to the accomplishment of the objectives described above, this invention consists of the features hereinafter illustrated in the drawings, fully described in the detailed description of the preferred embodiment and particularly pointed out in the claims. However, such drawings and description disclose but one of the various ways in which the invention may be practiced.